The present invention relates to a method for measurement of viscosity change, for example, a blood coagulation process, as well as a sensor used to perform said method.
Generally, determination of a viscosity change occurring in blood or the like is important to know actual conditions of blood or the like and, for example, enables a blood type to be easily identified.
Furthermore, the determination of the viscosity change has been commonly used to diagnose so-called hyperviscosity diseases such as cerebral infarction and myocardinal infarction.
Especially, blood coagulation is particularly important and determination of the coagulation time has been most commonly used for diagnosis of various diseases such as haemophilia, von Willebrand's disease, Christmas disease and hepatic diseases. Pathologically, it has also been put in practice to know a condition of immune reaction by reacting plasma in blood with antigen or antibody.
Typical method for measurement of blood coagulation time which have conventionally employed include those relying on measurement of prothrombin time (PT), measurement of activated partial thromboplastin time (APTT), measurement of thrombin time, fibrinogen test and hepaplastin test.
Typical methods for examination of immune reaction include those relying on examination or measurement of complement supply reaction, fluorescent reaction and enzyme immunity.
With the conventional methods for measurement of viscosity change in blood or the like, determination of coagulation or other phenomena have been macrographically made in most cases, even through these methods have utilized stimulators and test reagents which are commercially available and contain therein predetermined stabilized ingredients. Subjective judgment of the operator has necessarily limited the reliability of measurements and the measuring procedure usually repeated to improve such reliability of measurement has often resulted in unevenness of the measurements.
It is also well known to measure blood coagulation time by use of a mechanical apparatus, for example, through determination of prothrombin time by use of spectrophotometer. However, such method of well known art is disadvantageous in that any disturbance on top of liquid to be tested will cause light scattering which, in turn, will cause a measurement error.
Not only this method utilizing the spectrophotometer but also the other methods of prior art by which the blood coagulation time is measured by use of the mechanical apparatus have inconveniently been complicated also in their mechanisms.
The inventors disclosed a method for measurement of physical property change occurring in liquid or the like in Japanese Disclosure Gazette No. 1985-152943. The disclosed invention proposes, as a part thereof, the method closely related to the present invention, i.e., the method for detection of any thrombus formed on the inner wall of artificial blood vessel through a change of heat transfer coefficient as sensed by a sensor utilizing metallic wire which is fixedly arranged in the inner wall of said artificial blood vessel. However, such method intends only to detect formation of thrombus on the inner wall of the artificial blood vessel but not to detect any abnormal condition occurring in blood or plasma itself.